This is a lot less complicated than it appears. Given a set of sentences, each belonging to a class, and a new input sentence, we can count the occurrence of each word in each class, account for its commonality and assign each class a score. Factoring for commonality is important: matching the word “it” is considerably less meaningful than a match for the word “cheese”. The class with the highest score is the one most likely to belong to the input sentence. This is a slight oversimplification as words need to be reduced to their stems, but you get the basic idea.
One of the more talked about integrations has been Taco Bell‘s announcement that it is working on a Slackbot (appropriately named Tacobot) which will not only take your Gordita Supreme order but will do it with the same “witty personality you’d expect from Taco Bell.” Consumer demand for such a service remains to be seen, but it hints at the potential for brands to leverage Slack’s platform and growing audience.
Utility bots solve a user's problem, whatever that may be, via a user-prompted transaction. The most obvious example is a shopping bot, such as one that helps you order flowers or buy a new jacket. According to a recent HubSpot Research study, 47% of shoppers are open to buying items from a bot. But utility bots are not limited to making purchases. A utility bot could automatically book meetings by scanning your emails or notify you of the payment subscriptions you forgot you were signed up for.
Specialized conversational bots can be used to make professional tasks easier. For example, a conversational bot could be used to retrieve information faster compared to a manual lookup; simply ask, “What was the patient’s blood pressure in her May visit?” The conversational bot will answer instantly instead of the user perusing through manual or electronic records.
Yes, witty banter is a plus. But, the ultimate mission of a bot is to provide a service people actually want to use. As long as you think of your bot as just another communication channel, your focus will be misguided. The best bots harness the micro-decisions consumers experience on a daily basis and see them as an opportunity to help. Whether it's adjusting a reservation, updating the shipping info for an order, or giving medical advice, bots provide a solution when people need it most.

Interface designers have come to appreciate that humans' readiness to interpret computer output as genuinely conversational—even when it is actually based on rather simple pattern-matching—can be exploited for useful purposes. Most people prefer to engage with programs that are human-like, and this gives chatbot-style techniques a potentially useful role in interactive systems that need to elicit information from users, as long as that information is relatively straightforward and falls into predictable categories. Thus, for example, online help systems can usefully employ chatbot techniques to identify the area of help that users require, potentially providing a "friendlier" interface than a more formal search or menu system. This sort of usage holds the prospect of moving chatbot technology from Weizenbaum's "shelf ... reserved for curios" to that marked "genuinely useful computational methods".